A classical computer performs operations using

classical bits, which can be either zero or one. Now in contrast, a quantum computer users

quantum bits or qubits. And they can be both zero and one at the same time. And it is this

that gives a quantum computer its superior computing power. There are a number of physical objects that

can be used as a qubit. A single photon, a nucleus or an electron.

I met up with researchers who were using the outermost electron in phosphorous as a qubit.

But how does that work? Well, all electrons have magnetic fields, so they are basically

like tiny bar magnets. And this property is called spin. If you place them in a magnetic

field they will align with that field, just like a compass needle lines up with the magnetic

field of the earth. Now this is the lowest energy state, so you

could call it the zero state or we call it for the electron, spin down. Now you can put

it in a one state, or spin up, but that takes some energy.>>If you took out the glass from your compass

you could turn the needle the other way, but you would have to apply some force to it.

You have to push it to flip to the other side. And that is the highest energy state. In principle,

if you were so delicate to really put it exactly against the magnetic field, it would stay

there.>>Now so far this is basically just like

a classical bit. It has got two states, spin up and spin down, which are like the classical

one and zero. But the funny thing about quantum objects is that thy can be in both states

at once. Now when you measure the spin it will be either up or down. But before you

measure it, the electron can exist in what is called a quantum super position, where

these coefficients indicate the relative probability of finding the electron in one state or the

other. Now it is hard to imagine how this enables

this incredible computing power of quantum computers without considering two interacting

quantum bits.>>Hello.

>>Hi. Now there are four possible states of these

two electrons.>>You could think that, well, that is just

like two bits of a classical computer, right? If you have two bits you can write zero, zero;

zero, one; one, zero; one, one. Right? There is four numbers. But these are still just two bits of information.

Right? All I need to say to determine which one of the four numbers you have in your computer

code is the value of the first bit and the value of the second bit. Here, instead, quantum

mechanics allows me to make super position of each one of these four states. So I can

write a quantum mechanical state, which is perfectly legitimate, that is some coefficient

times this plus some coefficient times that plus some coefficient times that plus some

coefficient times that. So determine the state of this two spin system,

I need to give you four numbers, four coefficients, whereas in the classical example of the two

bits, I only need to give you two bits. So this is how you understand why two qubits

actually contain four bits of information. I need to give you four numbers to tell you

the state of this system, whereas here I only need two. Now if we make three spins, we would have

eight different states and it could give you eight different numbers to define the state

of those three spins, whereas classical it is just three bits.

If you keep going, what you find is that the amount of equivalent classical information

contained by N qubits is two to the power N classical bits. And, of course, the power of exponentials

tells you that once you have, let’s say, 300 of those qubits in what we call the folient

angle state, so you must be able to create these really crazy states where there is a

super position of all three angles being one way and another way and another way and so

on, then you have like two to the 300 classical bits, which is as many particles as there

are in the universe.>>But there is a catch, although the qubits

can exist in any combination of states, when they are measured they must fall into one

of the basis states. And all the other information about the state before the measurement is

lost.>>So you don’t want generally to have as

the final result of your quantum computation something that is a very complicated super

positional state, because our cannot measure a super position. You can only measure one

of these basis states.>>Like down, down, up, up.>>Yeah. So what you want is to design the

logical operations that you need to get to the final computational result in such a way

that the final result is something you are able to measure, just a unique state.>>That is not trivial.>>That is not trivial. And it is essentially

… I am kind of stretching things, but I guess it is to some degree the reason why

quantum computers are not a replacement of classical computers.>>They are not.>>No, they are not. They are not universally

faster. They are only faster for special types of calculations where you can use the fact

that you have all these quantum super positions available to you at the same time, to do some

kind of computational parallelism. If you just want to watch a video in high definition

or browse the internet or write some documenting work, they are not going to give you any particular

improvement if you need to use a classical algorithm to get the result. So you should

not think of a quantum computer as something where every operation is faster. In fact,

every operation is probably going to be slower than in the computer you have at your desk.

But it is a computer where the number of operations required to arrive at the result is exponentially

small. So the improvement is not in the speed of the individual operation. It is in the

total number of operations you need to arrive at the result.

But that is only the case in particular types of calculations, particular algorithms. It

is not universally, which is why it is not a replacement of a classical computer.

## 100 Comments

## Guest Channel

Best explaination till this date!

## bert wesler

If you people believe in quantum this and quantum that you are a bunch of retards!

## Warren Sanchez

Explain it to me like im five. – Michael Scott hahaha

## ailan shangpliang

Its like explaining Calculus to a stone age human. How on earth do these people even communicate with the sub atomic particles or whatever and get them to work?. mind bogging

## theartliving

Quantum conputing is a theory based delusion. So its important nobody understands. So they can fool people.

## Christopher Zielinski

Morello is providing his doubts, only true scientist does that, I like it

## thousand points of light

a quantum bit ie a unit of light cannot be a one and zero at the same time.

light is polarized, meaning it has its own magnetic field, a computer uses

magnetic fields to name bits ones or zeros, a bit or unit cannot be both a

one and a zero at the same time. what this is speaking of are fallen angels

who are androgynous, ie both sexes, female body, male genitals.

## soroush moallemi

Could you please explain how we can detect these spins? It seems we need very sensitive sensors to determine the spin of the electron

## Omnia Bella

what kind of math is this exactly? [I really need to know this, or i'm getting steamrolled by the teacher]

## Tyler Eury

Doesnt that mean that they could create super defense systems against malware? Making hacking impossible with a normal computer? Idk

## Stepler Velikiy

Wow! I’m a bit shocked, because today i had a lecture in the university about the quantum superposition! Is it a coincidence that i have this video in my recommendation list?

## Billy Joe

It doesn't.. 😂

## longnameyeshowmanycharacterscanifitinhere

i wonder if it could handle minecraft with ray tracing

## Mike G

"They can be a zero or a one at the same time"

I don't get it.

## MarufIaM

The guy explaining is in a super position of human. he is in Both Male and Female form at the same time 🙂

## serzhsom

Нихуя не понял, но очень интересно.

## tropicwave1

mid 2013

## Sarah Adams

Is because of overheating?

I think so.

## Rani Owais

It looks very awesome interesting to me but takes much of your mind i did not get athing

## Menya Savut

is there any sane reason why you constantly move the camera, when you record Andrea? thumbs down for one of the worst cameraman.

## Neo Roman0

Another video about quantum computing that doesn’t fulfill its promise :/

## Damo Diggler

"2 to the dree hundred classical bits ah ah ah" – Sesame street's The Count.

## edgy circle

the comments on these type of videos are so funny cus its too true

## Heroix

2:50, does this suggest that a multiverse simulation would be possible in the near future

## Tranzor Z

very well explained. thank you.

## Andrew Carfax-Foster

1:40 finally got it here after watching so many videos… these few seconds made it

## katakis1

He does a great job at explaining it. Picks his words with great care. Now I want to know which types of calculations would benefit from quantum computing.

## AJ Was

Not understanding this makes me really mad.

## Jimmy Hunt

Totally forgot I was watching this. Thank god for smart people.

## MissPickleHeads

can the camera man stay still omg

## Jacob Ray

What

## John Heo

who's here after Google released their first quantum supremacy ?

## Albert Souza

Wtf did he just say!

My brain just shattered in a million places.

That's why he makes the big bucks

Dammit I should have hung out with geeks! lol

## Tursun Elyar

who is here after google quantum supremacy claim

## sky kad

Thank God my job is safe…ufff

## Adnan Khan

lecture is out of my skull

## The_DankSmith

100% of people who watched the video understood everything but the other 100% of them didnt understand anything

and thats called a superposition## tinyentropy

What’s the difference of this parallelism to a non-deterministic Turing machine?

## Petr Antoš

well, about information storage, the 2 power to 300 (why the hell the number is not also power of 2?), its simply say 40 bytes, so why the hell somebody wants to "enwow" somebody by explaining this and this shitty way? I understand its about some crazy paralel computations and very specific use cases, but as he perfectly described, even encoding such info into field of qubits is far far far far more complex, not to mention almost quantum-physically impossible decoding it – and nobody was talking about some basic functional parallel ""ALU"" (arithmetic-logical-unit) yet, so I am sure almost nobody knows how to use it all to do anything usefull now and I am almost (un)certainly sure that nobody will know how to do it during next few decades still )), .. yet, unsure

## Martin The Panda

That professor looks like a surfer from the 90s.

## David Lotti

I’m still trying to understand my 1964 6 transistor radio and where are the tubes located in my new TV ?

## belstar

So a quantum computer is basically a analog computer?

## Jiimy

Bought here by google

## this is me

I got los in 0 and 1

## Muhammet Yıldız

The guy is amasing.

## K U

Thank you for Sharing this information; I have a better understanding in how these work and assurance that Skynet isnt taking over the world anytime soon!

## Nhat

the hardest part to understand is the both states at the same time, it makes us confuse but it's just the way it is, it's a property of quantum particles, it doesn't follow our physics rules

## Ian Lonergan

I’d like to find out how they actually program a quantum state computer, actually at a guess it would be beyond me to appreciate.

I get to this stage each quantum bit (q-bit) has a capacity of being both 1 and 0 but as a probability of being both 1 and 0 at the same time. I could be wrong and sadly I’m probably will be but if one actually measures the actual position of a q-bit it should collapse like in a wave function of a split screen collapses when a photon is measured if it is going this way or that way. However before measuring the photons path the photon was “happy” going through both slits.

Then they talk about having a series of q-bits which then increases the computational power by having these suppositions nested as each q-bit being so much of this and so much of that at the same time. My brain hurts……..like I got me a pair of gloves but I’ve put them on back to front only to find my little pinky don’t work like my thumb. Noooooooooo! I don’t care how safe it is I ain’t gonna drink any milk until I know wether I’m dead or alive or both or should I say a probability of being both dead and alive.

Drink it Freddy it’s good for you! Gulp!

## Narendra Roy

Somebody please correct me if I am wrong. So.. Quantum computing according to him helps in problems that require too many parallel processes to arrive to answer but when it comes to problems which intrinsically demand sequential processing, it fails to provide us any better alternative than a normal classical bit system. Is it so? Speaking of the mechanics of its working, is it like we want to store as much variability as possible in the system which can be handled but with a sense that that should ultimately map back to our earlier idea of standardized states. So, we employ to some complicated linear/non-linear sum of probability values of spin states and then finally divide the output (values)space of that combination into some non-overlapping partitions which then serves as a well defined region for us to map as some classical bit state?

## Adam Nowak

This guy Andrea is doing a really good job explaining quantum computers. Most of the materials about it that i stumbled upon seem like the authors don't get the idea themselves. He sounds like he's having some deep understanding of the topic

## Shaikh Shariq

My mind is in superposition right now

## M Gabrielle

Thank God quantum computer cannot and will not replace my old pc. And a bit silly to rely on uncertainty of qubits, they can be both in a supper position I.e 1 and 0 at the same time, oh yes, who the heck do you think you are fooling? Why not say quantum computer only works on guesses, so the results would be just a fluke guess.

## 500seriously

With one of those i could watch and not watch this video at the same time

## Arno Inen

To simplify… one qubit can act like it is two bits (two switches) Two qubits like four. Three qubits like eight. Etc.

That's the revolution.

## AcidBot66

I am still to see someone who explains how to use uncertainty and extract useful, predictable and reliable processing results.

## anant navgire

It amazing

Didn't understand anything.

## vraj patel

Did anyone watched this video after google achieved quantum supremacy

## M Gabrielle

Also my wife is a quantum bitch, she be with me one minute and the next minute she is with someone, she is calculating who is better and it has taken her 10 years so far to arrive at any conclusion one way or another, so I am glad she is in a super position and neither here nor there or screwing me thinking its him, she is with me at the same time she is with him, really that is not an impossible state to be ! she is a real quantim bitch and can be everywhere at the same time. You cannot comprehend that only I know! .

## Juan Manuel

Were do you get 10 million billion input parameters to define the states of 53 qubits?

## Kardo Salih

thanks

## john smith

right this is my second "how quantum computers work" vid and I'm now finding myself not caring how the fecking things function

## Saibal Ray

Next life goal :

Get Andrea Morello's autograph

## ny mosley

Thank you. The use of the coefficients demystified the the process.

## Kedarnath Rajeevkumar

with one bit we can only represent a 0 or 1 ie; one digit but with one qubit we can represent 2 digits 1 and 0 similarly with 2 qubits we can represent 4 digits 00 01 10 11 @same time but with 2 bits we can represent only 1 and 0

## M_Faraday

Question: at 1:17 he says that if you put it

exactlyagainst the magnetic field it would stay there. Is this just Buridan's ass but with electrons?## Dennis Kean

I have read up about this nonsense for years. Having a perfect score in all my years of math study I can honestly say that this is totally ridiculous. There is nothing and no advantage to be gained mathematically with switching from indeterminate to a defined state. Universities use this as a cash cow for getting funds and doing nothing more than talking. It is just like the environmentalists. "Give me lots of money and I will pacify you if you give me enough".

## Ben Basic

I wonder if there's an example of a simple problem that can be solved by quantum computation.

## Duangrat Tualek Poonsuk

amazing, thanks.

## seyed mahmoud

I haven't quantum qomputer

## SËç0ñ d LIFE

Give his eye brows back to him ….or he will attack you with math…

## monkgroupie

the camera man must be drunk. Stop going back and forth, I'm getting dizzy.

## Quoise

uh huh….yeah…ok…. oh really?…. ohh I see. Yeah, yeah, ok! (back to cat videos)

## Avihai Melamed

I’ve watched seven teen videos on this and have yest to see one complete example of a calculation

## Nigelssj9

Can it run Crysis ?

## ken pringle

Wow ! I cannot get pass that Adams apple…😱

## Roberto Giménez

You don't need to use plastic to make your video.

## dokha

4:15 right back into seseme street it made me lol honestly

## divyansh varshney

That guy has a weird beard !🙀

## samarth here

Nope still not getting it.

## nishant jhala

don’t need to wait for quantum computers to come as it’s not a replacement of classical computer. We can buy the existing classical computer as it’s not going to change our type of computer usage, we won’t regret buying the classical computer even if the quantum computer is launched next day. so chill.

## Zac Dior

Ladies and gentlemen..

I give you…

The Quanputer. 🙂

## lamarincho

Brought to you by………Werner Heisenberg, Erwin Schrodinger and Max Planck.

## Only Alex

Someone copied this video!! Link is here… https://www.youtube.com/watch?v=Fv-7P27NvAQ

## Lysol

Quantum Mechanics…

I understand it.

I don't understand it.

## Seudon Amous

It would be a requirement of the virtual reality we are living in though. What we need now is a quantum computer in the VR world to help the Quantum Computer in the real world do its job.

I am old and the glitches have become noticable…. It was a little traumatic

## Ferdinand Louise

I am pretty bad at math, so i don't understand lol

## Ross Sives

I bit off more than I could chew with this topic

## Haxl Waxl

So do i get 240FPS with it or not?

## Sofia Grafa

0 + 1 = Φ

## jassonsw

I still haven't heard a decent explanation of quantum computing. I get qubits, I get entanglement but how the hell do you make that system perform any calculations? How do you manipulate the qubits so they do something useful? They never explain the guts of it properly, they always talk in analogies. "It's like this" or "It's like that". Don't tell me what it's LIKE tell me what it bloody well IS!

## Nigel Olsen

Hey baby, do you want to try the quantum super position? (Joke)

## Victor Tong

I watched this video couple times, there are couple things I still haven’t figure it out.

If the results can only reveal at the end at once,

So it is quantum memory to reveal the true state, once it is reveal it changes, but the state is fuzzy state , which also the best guess of something.

And u mention it’s works out the same for all the lightbulbs or whatever have electron , which implies it can build with any materials.

If so, then we can build it at home?

## SYLperc

I think i get it..

A classical computer is faster for single computations. It does one thing at a time very quickly. And as every bit it has available increases, it can do another single computation per bit available – this is a linear increase.

For quantum computing, it can do a single computation per bit available. However, when you add available bits, it can run in parrallel an exponential number of computations.

The difference is noted when the computing power is used for finding results of a function with a changing variable. A classical computer must run each equation one bit (or 2) per t time, and if there are n bits, it will run at 2n bits per t time. Whereas with a quantum computer, it can run a function at one bit (or 2) per t time, and with n bits, 2^n bits per time.

So for say trying to find the encryption password for any secure network, quantum computing will find it exponentially faster than classical computing.

## Anuj Topiwala

So technically using two qubit is equivalent of quad core computer for some problem and 64 qubit is 2^64 core computer.

## Email Alpha

I have not been able to find a video on quantum computers that went beyond the physics. Imagine looking for a tutorial on Javascript programming and every video you find talks about transistors. Does anyone know of a good video on how programming quantum computers actually works??

## jamal Mentalist

NOTE: your Arabic subtitles is wrong

## ADITYA Rathore

After watching this upload i forgot counting beyond 0 and 1

## Eric Dary

Is he going to mention up qurks and down qurks?

## Renato Medeiros

So a quantum computing is a womans brain simulation?

## M 5

Stop the floating camera. I can understand him better if your camera stops floating between him and the board,